But a simpler interoperability deal between Skype and Microsoft's corporate messaging service Lync would make a lot more sense than a straight acquisition.

Skype's corporate team was reportedly working around the clock this weekend getting ready for a major partnership announcement this week. Last week, Facebook was rumored to be considering a buyout or joint venture, which would help boost the messaging product Facebook introduced last year.

Google was also supposedly looking at a joint venture, although it's hard to see how Skype would add to what Google already has with Google Talk. But Google might take the plunge just to keep Skype out of Facebook's hands.

What about Microsoft?

Microsoft already has voice and video chat in Windows Live Messenger for consumers, and voice chat plus video conferencing in Lync and Lync Online for businesses. It's very hard to see what Skype would add to either product, other than a stronger brand name for consumers.

Microsoft might be interested in Skype for some intellectual property or a piece of technology, but at $3 billion plus, that's an expensive technology acquisition.

Finally, Microsoft has been very shy about doing acquisitions in the last couple of years -- particularly large ones.

What's more likely: some sort of interoperability deal between Skype and Lync (and Lync Online) so that customers of one service can easily look up contacts and place calls to users on the other service. That would help Skype make inroads into the enterprise and add a frequently requested feature to Lync.

Microsoft might make a small investment to convince Skype to do the deal, just as it did with Facebook back in 2007 to get an advertising deal. That turned out to be one of the best investments Microsoft ever made.